Abstract

The synthesis and characterisation of a series of novel bis(imine)copper(I) complexes and their use in atom-transfer polymerisation of methyl methacrylate is described. Several N-alkyl-(2-pyridyl)methanimines (alkyl = n-butyl, isobutyl, sec-butyl, n-propyl) and N-(n-propyl)-1-(2-pyridyl)ethanimine as ligands have been fully characterised. Three bis[N-alkyl-(2-pyridyl)methanimine]copper(I) complexes, [Cu{(C5H4N)CH=N(iBu)}(2)][BF4], [Cu{(C5H4N)C(CH3)=N-(nPr)}(2)][PF6], and [Cu{(C5H4N) CH=N(sBu)}(2)][BF4] have been structurally characterised; all having a distorted tetrahedral arrangement of co-ordinating nitrogen atoms surrounding the metal centre. All of the catalysts were found to be effective atom-transfer polymerisation catalysts for the polymerisation of MMPI in hydrocarbon solution. However, it was discovered that the performance of the catalysts containing n-alkyl substituents was superior to those containing branched alkyl substituents. The presence of branching in the alkyl substituent results in a reduction of reaction rate and a corresponding broadening of the polydispersity index.